pinto turbo air/fuel

[2010deathproofcapri]

Who has self tuned their pinto turbo setups? What sort of afr have you found o be most ideal? Do you run rich at idle and part throttle? I'm hoping to set up the carb so I'm running around 14:1 at idle and part throttle and around 12:1 at 10psi and wot. Would this be too rich?

[theduck]

I would say not rich enough and to be happy would want 11.something:1 when under boost and wot

[katana]

There is NO ideal - every engine and installation is different and will NEED different numbers. You'll only find out on a dyno or datalogging under load - fine tuning by 'seat of the pants' with turbos can be costly. The numbers you quote are ballpark but the engine might prefer half a ratio up or down - easier with EFI but harder with carbs.

[MK1_Oz]

So what gear do others use in-car when monitoring afr on track/road? Is such gear as accurate as that used by the dyno tuners?

[katana]

A standalone AFR gauge or datalogger is as accurate as a dyno facility machine - they will likely use the same sensors! The same wideband sensors can be used with certain ECU's to 'self learn / tune' fuel maps and monitor fueling continuously whilst driving and making adjustments to refine the fuel map they are to a degree making dyno's redundant although ignition timing can be more crucial and yet knock sensing hasn't been widely adopted in aftermarket controls - so is best still done on a dyno IMO.

[stevieturbo]

So what gear do others use in-car when monitoring afr on track/road? Is such gear as accurate as that used by the dyno tuners?

That depends what gear the dyno tuners use.

[Dyno]

Turbo engines need richer mixtures to survive. There is no ideal AFR number for any tuned engine. 14 at idle will be lean for a Pinto. At WOT you need extra fuel, I try to tune at the "rich side" without lost of power. Opposite to NA engines, except some air cooled setups who also need more fuel to stay alive.

The good thing about turbo engines is, the cam is soft and Lambda is not confused. So if you dial anything between 11 and 12 it will be OK. Richer as 11 is usual drop in power but depend what engine you are tuning. I recently also completed some tests around size of droplets, AFR reading and engine power + engine response. I can't share any info but I was surprised the size of the droplets made such a big influence on power and AFR reading was far from a reliable factor. So changing from one type of injector to an other or position can be a big difference. In one occasion I was testing on a 120 Bhp engine, the difference between the best and worse droplets made a difference of no less than 5 Bhp without any other changes and fuel corrected for optimum. Test work was done on carbs but 100% sure the same will be the case with fuel injection.

[therealpinto]

I actually have my Pinto idling at close to lambda 1 or 14.7. It's not a super stable idle but works to please our emission test at the bi-annual MOT...

At WOT I try to aim for 12:1 or a tad richer. But that is on an engine with low compression ratio so it's perhaps a bit more tolerant?

Also, running engine management with mapped timing helps I guess. With a standard dizzy the margins are smaller.

Regards

Gustaf

[Dyno]

Yes, need to do the same for MOT here but will idle better richer. Nothing as a "correct" AFR, also depend how much boost you want and how save you want or need to be.

Mapped ign. can be easier but never found a single issue using distributors on a low boosted engine. Higher boosted engine, both used for road en race can be more tricky. Sometimes difficult to mod the vac / boost canister over full range. But believe me, the window you can work in for a correct setup, save engine is big enough. It's again a compromise between save and sorry. But don't think low ignition numbers are so save for a turbo, you get opposite.